Priorities for Lung Transplantation Among Patients With Cystic Fibrosis—Reply

In Reply: It is encouraging that Dr Liou and colleagues carefully considered the potential impact of the rate of fall of FEV₁% in developing their model for predicting survival in patients with cystic fibrosis. They state that despite a variety of iterations of the model they were unable to find an impact on the survival predictions, and they conclude unequivocally that "the rate of decline in FEV₁% is not helpful in the selection of candidates with CF for lung transplantation." However, they also note that this clinical parameter has been identified as a negative predictor by several other authors.^1- 3 It is important to remember that the model has not yet been validated prospectively in patients with CF who are within their last years of life. The disparity between the model of Liou et al and other published data in predicting 5-year survival likely reflects the different populations studied. Authors who have identified the rate of decrease in FEV₁% as an important predictor have generally not looked at the whole population of patients who might be included in a 5-year survival prediction model, but rather at a smaller subset of patients, a "self-selected" group, who are rapidly deteriorating clinically. In this population, the rate of decline of FEV₁ might indeed be helpful to caregivers and transplant centers in determining appropriate times to wait-list patients. Whether the addition of this type of parameter to the predictions of the model of Liou et al adds useful information for clinicians will become clear as it is evaluated prospectively.